Audi 80/Avant (B4)

Since 1991-1995 of release

Repair and car operation

On an illustration the distributive Torsen-differential in a cut is presented.

If will establish authorship of any firm in a question on introduction of a full drive for serial cars «in a decent society» it, undoubtedly, will give Audi.

The off-road car «VW Iltis», developed by request of the Bundeswehr firm Audi for Volkswagen, most likely, has served as a germinal cage for idea quattro (a full drive). The legend says:

During a winter trip to Northern Sweden one modest «Iltis» has far overtaken much more powerful and fast front-wheel Audi. After that the head of tests of a running gear of that time has wished to have «the all-wheel drive car with sufficient capacity» as the daily car. And as it is known that there is nothing more strongly the idea which time has come (and this idea, appear, was such), over the concept worked until has been presented legendary Audi quattro.

Concepts of a full drive

Connected full drive

Until recently the concept of "the all-wheel drive car» was almost inseparably linked with concept of "the off-road car». The concept of a full drive of the last was simple enough: to a standard drive (the engine ahead, the drive back) has been simply attached one more drive, namely to the forward bridge one more transmission through a distributing box and additional карданный conducted a shaft.

Trips were carried out usually with a standard drive and only in the event that it was demanded by position on road, the forward drive was connected. This design with a connected full drive and is today usual for cars of the raised passableness (off-road cars).

Lack of similar system: at trips on a firm covering the full drive should be disconnected, because on turns forward wheels pass longer way, than back. Various frequency of rotation of wheels lead to difficulties with management.

Constant full drive

So, if the idea has come to a head to create the constant full drive constantly operating on all four wheels it is necessary to create the device preventing проскальзывание of wheels. This problem is solved by so-called interaxal differential.

Differentials in motor industry are known for a long time. They distribute a twisting moment between right and left driving wheels.

There too it is necessary to counterbalance forces because, as it is known, the external wheel takes place on turns longer piece of a way, than internal. The balance weight role incurs axial differential. He allows to transfer the moment on both drivers wheels depending on angular speed of each of them.

In the winter, for example, happens so: the wheel standing on ice is turned, and the opposite wheel on a rough covering does not transfer any force and consequently costs. Clearly one: the similar differential is not necessary for a role interaxal because it is necessary to achieve opposite effect. Force should be transferred there where wheels can move the car. Namely there, where the road covering possesses good coupling. And as the driver never it foreknows, distribution should occur automatically.

After various development cycles, including interaxal differential blocked manually, all-wheel drive models Audi quattro today are completed by so-called Torsen-differentsialom.